The proposed study will develop a novel, high dynamic range multi- frequency transducer array designed for broad-band tissue imaging. The new array would utilize elements of the same or different materials resonating in different thickness modes to permit operating at the subharmonic, first harmonic and second harmonic frequencies. One element will be optimized for transmit and the other two optimized for receive. In this study, the first harmonic transmit/receive frequency will be 5.0 MHz with corresponding subharmonic and second harmonic echoes at 2.5 MHz and 10.0 MHz, respectively. In Phase I, Layered Manufacturing Inc., with the support of the Center for Ceramic Research of Rutgers University, will develop a small co-linear array of three parallel arrays at three different frequencies. The piezoceramic transducer arrays will be fabricated utilizing patented layered manufacturing techniques that are ideally suited for the frequency regime common to medical imaging (1-10 MHz). A feasibility demonstration will include the measurement of the scattered echo returns from a fluid with a microbubble- based ultrasound contrast agent. In Phase II, a 2-D array will be fabricated, interspersed with multi-frequency transducer elements, and the various imaging modes used to image animals, with and without an ultrasound contrast agent. PROPOSED COMMERCIAL APPLICATIONS: If the design of a multi-frequency transducer array proves successful, then Layered Manufacturing Inc. is prepared to license the technology to all ultrasound system companies. LMI is also prepared to commercially provide special transducer arrays for specific applications, particularly at high frequencies, above 10 MHz.